METHOD FOR THE PREPARATION OF N-SUBSTITUTED CARBAMIC ACID SALTS

METHODE POUR LA PREPARATION DE SELS D'ACIDE CARBAMIQUE A SUBSTITUANTS EN N

English Abstract

METHOD FOR THE PREPARATION OF N-SUBSTITUTED
CARBAMIC ACID SALTS . -
ABSTRACT OF THE DISCLOSURE . -
A method is disclosed for preparing
salts of the N-substituted carbamic acid, the
improvement consisting in that the amine corresponding
to the nitrogenous substituent of the carbamic acid
is reacted with carbon dioxide and a salt of the
metal to be introduced in the carbamic acid molecule.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A method for the preparation of salts of
N-substituted carbamic acid having the general formula:
<IMG>
wherein R and R' are identical or different and each represents
hydrogen or an alkyl, aryl, cycloalkyl or aralkyl radical, with
the proviso that R and R' cannot simultaneously represent hydrogen,
Me is a metal selected from Groups IA, IIA and IIB of the Periodic
Table and n is 1 or 2, which comprises reacting in a single step
an amine of the formula
<IMG>
wherein R and R' have the aforesaid meanings, with carbon dioxide
and an inorganic salt of the aforesaid metal in an alcoholic
solvent.
2. A method according to claim 1, wherein the reaction
is carried out in a low alkanol.
3. A method according to claim 1, wherein the reaction
is carried out at a temperature comprised between the freezing
point and the boiling point of the alcoholic solvent or the
amine.
4. A method according to claim 3, wherein the reaction
is carried out at a temperature between 0° and 60°C.

Description

.:
This invent~on relat~s to the preparation of salts of :~
~ the N substituted carbamic acid having th~ follow~ng general.. formu~a : / \ .
. ~ - N - C - ~
~` R' o ~ ~e
; wherein R and R~ can be alkyl~ aryl, cycloalkyl or aralkyl
;.,
radicals, either saturated or unsaturated, or, as an alterna- :
. ti~e, but not æimultaneously, hydrogen, Me is a metal of the
Groups IA~ , or IIB of the periodic Table~ and n is an
!~ lo .inte~er sel~cted between 1 and 2~ said method heing bas~d ~;
~ on the reaction of the corre0p~nding amines with carbon
;~ dia~ide ard with salts of said metals in an alcoholic s~lvent~ -:
The reactiqn can be su~marized by the fall~wing
equation : R"OH I
n ~ n C02 ~ n R- N - H~ R ~ o Me ~ HX
. wherein Mej N, R and R' have the meanings as çx~lained above,
~ i' is an alkyl radical~ X i~ an ami}le. Anions~ the me~al
.j derivativ~s of w~ich are especially used, are CO= SO3~ 0
;.~ 20 OH~ S=, SHJ Cl~ and others; for example co~pou~ds such as LiCl~
~i ~ Li2C03~ CaOJ K2~03~ KCl le~d themselves well. Among the
amine~ a ~pe~ial mention is reserved by propYlamine, diethyl
amin~j N,N~-~lmethyle~hyl~nediamine, whereasj among the solvents~
the us~ is ta be emphasiz~d of meth~nol and ethanal,
The~reac~ion tak~s place by causing a carbon dioxide
s~ream to bubble ~hrough a solution or suspension of the select-
d salt ln the pre.sence of amine. A prçssure of CO~ up to 10 :
. .
:~ .
.. ~, ~. .
.:1~ - ,. :
,.', ' ' ~

kilo~rams per square centim~ter is preferred~
The temperature is maintained between th~ freezing point
teimperature o~ the alcohol or the amine and th~ boiling point,
and preferably between 0C aind 600C.
I~ necessary a different solvent can also be employedj~ provi-
ded that it is inert towards the reaction concer~ed
The reaction products of interest herein are deposlted as
bulky precipitates: simultaneously~ acidic salts are formed if
the anion of the ~etal salt used as the starting material is
bivalent~ as can be seen in thie above r~ported pattern, whereas,
for example, the amine hydrochloride is formed if chlorides are
the starting salts.
The s~paration of the c~rbamates is carried out merely by
filtration when the by-pro~ucts are solu~le in the r~action
medium, or also by slurryin~ the reaction raw product in a
solvent which selectively dissolves the carbamates. In the
latter case it is poissible directly to operate in the presence
of such a solvent.
:j
~i EXAMPLE
Z0 4 25 grams of LiCl are dissolved in 50 ml$ methanol in the
presen~e of 12 grams of propylamine.
C0~ is caused to be absorbed by the mixture at room tempe-
rature and under a partial pressure of the gas equal to the ;
atmospheric~l pressure. A white precipitate is obtained which
;~ is collected on a filter and dried. There are obtained 8.o
~l ~rams of a product which proves to be LiOCONHCH2CH2CH3.
:.~
~i~ EXAMPLE
0.05 grams of K2C03 are slurried in 50 mls of CH30H in the
pr~sence of 15 grams of N~N'-dimethylethylenediamin~, 2 ~;~
is caused to be absorbed by the mixture at room temperature
~; with a partial pressurs of carbon dioxide of 1 atmosphere
3-
, :
:~ `, .
. . ,

~3~5~
N~arly immediately a white product is formed~ which is coll~ct-
ed on a filter ~nd dried.. Such a p~oduct, 14,8 grams~ is identi-
fied as CH3 - N ~ CH2 ~ CH2 N - CH3
;~ COOK COOK
In addition~ after a wh:ile~ a product which h~s been found
to be KHC03~ precipitate~ from the moth~r liquor.
.
EXAMPLE
3~5 grams of LiCl are dissolved ~n 25 mls EtO~ in the
pre~ence of 20 grams diethylamine
The mi~ture i6 subjected to C02 absorption und~r not too
., ~ .
~: drastic conditions (room temperature, C02 part. pressure 1
atmosphere.~ .
:~ A white produc~ is immediately formed~ which is identifiedas
Et NCOOLi ~9.2 grams). By adding ~t20 to the mother liquor
~3 Z
a produ~t is precipitated which is identified as -di~thyl- ~:
ammonium chloride (Et2NH HCi~
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